#include <vector>
#include <algorithm>
#include <cstdlib>
#include <complex>
#include <iostream>
using namespace std;
typedef complex<long double> point;
#define sz(a) ((int)(a).size())
#define all(n) (n).begin(),(n).end()
#define EPS 1e-9
#define OO 1e9
#define X real()
#define Y imag()
#define vec(a,b) ((b)-(a))
#define polar(r,t) ((r)*exp(point(0,(t))))
#define angle(v) (atan2((v).Y,(v).X))
#define length(v) ((long double)hypot((v).Y,(v).X))
#define lengthSqr(v) (dot(v,v))
#define dot(a,b) ((conj(a)*(b)).real())
#define cross(a,b) ((conj(a)*(b)).imag())
#define rotate(v,t) (polar(v,t))
#define rotateabout(v,t,a)  (rotate(vec(a,v),t)+(a))
#define reflect(p,m) ((conj((p)/(m)))*(m))
#define normalize(p) ((p)/length(p))
#define same(a,b) (lengthSqr(vec(a,b))<EPS)
#define mid(a,b) (((a)+(b))/point(2,0))
#define perp(a) (point(-(a).Y,(a).X))
#define colliner pointOnLine

enum STATE {
	IN, OUT, BOUNDRY
};

bool intersect(const point &a, const point &b, const point &p, const point &q,
	point &ret) {

	//handle degenerate cases (2 parallel lines, 2 identical lines,   line is 1 point)

	double d1 = cross(p - a, b - a);
	double d2 = cross(q - a, b - a);
	ret = (point(d1, 0) * q - point(d2, 0) * p) / point(d1 - d2, 0);
	if (fabs(d1 - d2) > EPS) return 1;
	return 0;
}

bool pointOnLine(const point& a, const point& b, const point& p) {
	// degenerate case: line is a point
	return fabs(cross(vec(a, b), vec(a, p))) < EPS;
}

bool pointOnRay(const point& a, const point& b, const point& p) {
	//IMP NOTE: a,b,p must be collinear
	return dot(vec(a, p), vec(a, b)) > -EPS;
}

bool pointOnSegment(const point& a, const point& b, const point& p) {
	if (!colliner(a, b, p)) return 0;
	return pointOnRay(a, b, p) && pointOnRay(b, a, p);
}

long double pointLineDist(const point& a, const point& b, const point& p) {
	// handle degenrate case: (a,b) is point

	return fabs(cross(vec(a, b), vec(a, p)) / length(vec(a, b)));
}

long double pointSegmentDist(const point& a, const point& b, const point& p) {
	if (dot(vec(a, b), vec(a, p)) < EPS)
		return length(vec(a, p));
	if (dot(vec(b, a), vec(b, p)) < EPS)
		return length(vec(b, p));
	return pointLineDist(a, b, p);
}


long double triangleAreaBH(long double b, long double h) {
	return b * h / 2;
}

long double triangleArea2sidesAngle(long double a, long double b, long double t) {
	return fabs(a * b * sin(t) / 2);
}

long double triangleArea2anglesSide(long double t1, long double t2,
	long double s) {
	return fabs(s * s * sin(t1) * sin(t2) / (2 * sin(t1 + t2)));
}

long double triangleArea3sides(long double a, long double b, long double c) {
	long double s((a + b + c) / 2);
	return sqrt(s * (s - a) * (s - b) * (s - c));
}

long double triangleArea3points(const point& a, const point& b, const point& c) {
	return fabs(cross(a, b) + cross(b, c) + cross(c, a)) / 2;
}

//count interior
int picksTheorm(int a, int b) {
	return a - b / 2 + 1;
}

//get angle opposite to side a
long double cosRule(long double a, long double b, long double c) {
	// Handle denom = 0
	long double res = (b * b + c * c - a * a) / (2 * b * c);
	if (res > 1)
		res = 1;
	if (res < -1)
		res = -1;
	return acos(res);
}

long double sinRuleAngle(long double s1, long double s2, long double a1) {
	// Handle denom = 0
	long double res = s2 * sin(a1) / s1;
	if (res > 1)
		res = 1;
	if (res < -1)
		res = -1;
	return asin(res);
}

long double sinRuleSide(long double s1, long double a1, long double a2) {
	// Handle denom = 0
	long double res = s1 * sin(a2) / sin(a1);
	return fabs(res);
}

int circleLineIntersection(const point& p0, const point& p1, const point& cen,
	long double rad, point& r1, point & r2) {

	// handle degenerate case if p0 == p1
	long double a, b, c, t1, t2;
	a = dot(p1 - p0, p1 - p0);
	b = 2 * dot(p1 - p0, p0 - cen);
	c = dot(p0 - cen, p0 - cen) - rad * rad;
	double det = b * b - 4 * a * c;
	int res;
	if (fabs(det) < EPS)
		det = 0, res = 1;
	else if (det < 0)
		res = 0;
	else
		res = 2;
	det = sqrt(det);
	t1 = (-b + det) / (2 * a);
	t2 = (-b - det) / (2 * a);
	r1 = p0 + t1 * (p1 - p0);
	r2 = p0 + t2 * (p1 - p0);
	return res;
}

int circleCircleIntersection(const point &c1, const long double&r1,
	const point &c2, const long double&r2, point &res1, point &res2) {
	if (same(c1, c2) && fabs(r1 - r2) < EPS) {
		res1 = res2 = c1;
		return fabs(r1) < EPS ? 1 : OO;
	}
	long double len = length(vec(c1, c2));
	if (fabs(len - (r1 + r2)) < EPS || fabs(fabs(r1 - r2) - len) < EPS) {
		point d, c;
		long double r;
		if (r1 > r2)
			d = vec(c1, c2), c = c1, r = r1;
		else
			d = vec(c2, c1), c = c2, r = r2;
		res1 = res2 = normalize(d) * r + c;
		return 1;
	}
	if (len > r1 + r2 || len < fabs(r1 - r2))
		return 0;
	long double a = cosRule(r2, r1, len);
	point c1c2 = normalize(vec(c1, c2)) * r1;
	res1 = rotate(c1c2, a) + c1;
	res2 = rotate(c1c2, -a) + c1;
	return 2;
}

void circle2(const point& p1, const point& p2, point& cen, long double& r) {
	cen = mid(p1, p2);
	r = length(vec(p1, p2)) / 2;
}

bool circle3(const point& p1, const point& p2, const point& p3, point& cen,
	long double& r) {
	point m1 = mid(p1, p2);
	point m2 = mid(p2, p3);
	point perp1 = perp(vec(p1, p2));
	point perp2 = perp(vec(p2, p3));
	bool res = intersect(m1, m1 + perp1, m2, m2 + perp2, cen);
	r = length(vec(cen, p1));
	return res;
}

STATE circlePoint(const point & cen, const long double & r, const point& p) {
	long double lensqr = lengthSqr(vec(cen, p));
	if (fabs(lensqr - r * r) < EPS)
		return BOUNDRY;
	if (lensqr < r * r)
		return IN;
	return OUT;
}

int tangentPoints(const point & cen, const long double & r, const point& p,
	point &r1, point &r2) {
	STATE s = circlePoint(cen, r, p);
	if (s != OUT) {
		r1 = r2 = p;
		return s == BOUNDRY;
	}
	point cp = vec(cen, p);
	long double h = length(cp);
	long double a = acos(r / h);
	cp = normalize(cp) * r;
	r1 = rotate(cp, a) + cen;
	r2 = rotate(cp, -a) + cen;
	return 2;
}

// minimum enclosing circle
//init p array with the points and ps with the number of points
//cen and rad are result circle
//you must call random_shuffle(p,p+ps); before you call mec
#define MAXPOINTS 100000
point p[MAXPOINTS], r[3], cen;
int ps, rs;
long double rad;

void mec() {
	if (rs == 3) {
		circle3(r[0], r[1], r[2], cen, rad);
		return;
	}
	if (rs == 2 && ps == 0) {
		circle2(r[0], r[1], cen, rad);
		return;
	}
	if (!ps) {
		cen = r[0];
		rad = 0;
		return;
	}
	ps--;
	mec();
	if (circlePoint(cen, rad, p[ps]) == OUT) {
		r[rs++] = p[ps];
		mec();
		rs--;
	}
	ps++;

}

//to check if the points are sorted anti-clockwise or clockwise
//remove the fabs at the end and it will return -ve value if clockwise
long double polygonArea(const vector<point>&p) {
	long double res = 0;
	for (int i = 0; i < sz(p); i++) {
		int j = (i + 1) % sz(p);
		res += cross(p[i], p[j]);
	}
	return fabs(res) / 2;
}

// return the centroid point of the polygon
// The centroid is also known as the "centre of gravity" or the "center of mass". The position of the centroid
// assuming the polygon to be made of a material of uniform density.

void polygonCut(const vector<point>& p, const point&a, const point&b, vector<
	point>& res) {
	res.clear();
	for (int i = 0; i < sz(p); i++) {
		int j = (i + 1) % sz(p);
		bool in1 = cross(vec(a, b), vec(a, p[i])) > EPS;
		bool in2 = cross(vec(a, b), vec(a, p[j])) > EPS;
		if (in1)
			res.push_back(p[i]);
		if (in1 ^ in2) {
			point r;
			intersect(a, b, p[i], p[j], r);
			res.push_back(r);
		}
	}
}

//assume that both are anti-clockwise
void convexPolygonIntersect(const vector<point>& p, const vector<point>& q,
	vector<point>& res) {
	res = q;
	for (int i = 0; i < sz(p); i++) {
		int j = (i + 1) % sz(p);
		vector<point> temp;
		polygonCut(res, p[i], p[j], temp);
		res = temp;
		if (res.empty())
			return;
	}
}

void voronoi(const vector<point> &pnts, const vector<point>& rect, vector<
	vector<point> > &res) {
	res.clear();
	for (int i = 0; i < sz(pnts); i++) {
		res.push_back(rect);
		for (int j = 0; j < sz(pnts); j++) {
			if (j == i)
				continue;
			point p = perp(vec(pnts[i], pnts[j]));
			point m = mid(pnts[i], pnts[j]);
			vector<point> temp;
			polygonCut(res.back(), m, m + p, temp);
			res.back() = temp;
		}
	}
}

STATE pointInPolygon(const vector<point>& p, const point &pnt) {
	point p2 = pnt + point(1, 0);
	int cnt = 0;
	for (int i = 0; i < sz(p); i++) {
		int j = (i + 1) % sz(p);
		if (pointOnSegment(p[i], p[j], pnt))
			return BOUNDRY;
		point r;
		if (!intersect(pnt, p2, p[i], p[j], r))
			continue;
		if (!pointOnRay(pnt, p2, r))
			continue;
		if (same(r, p[i]) || same(r, p[j]))
		if (fabs(r.Y - min(p[i].Y, p[j].Y)) < EPS)
			continue;
		if (!pointOnSegment(p[i], p[j], r))
			continue;
		cnt++;
	}
	return cnt & 1 ? IN : OUT;
}

const int MX = 100007;
	point a[MX];
	const long double pi = acos(-1);

int main(){
	int n;
	int px,py, x[MX], y[MX];
	cin >> n >> px >> py;
	long double MAV = 0;
	for (int i = 0; i < n; i++){
	   scanf("%d %d",&x[i],&y[i]);
	//	cin >> x[i] >> y[i];
		x[i] -= px;
		y[i] -= py;
		  a[i] = point(x[i], y[i]);
		  long double H= length(vec(a[i], point(0, 0)));
		  MAV = max(H, MAV);
	}
	//cout << MAV << '\n';
	long double MV = 1<<25;
	for (int i = 0; i < n-1; i++){
		MV = min(MV, pointSegmentDist(a[i], a[i + 1], 0));
	}
	MV = min(MV, pointSegmentDist(a[0], a[n-1], 0));
//	cout << MV << ' ' << MAV << '\n';
	long double ans = pi*(MV*MV - MAV*MAV);
	cout << fixed;
	cout.precision(9);
	cout << fabs(ans);
}